Tuberculosis (TB) remains a major global public health problem. About a third of the world's population is latently infected with Mycobacterium tuberculosis, and an estimated 8.7 million new TB cases were diagnosed in 2011 (World Health Organization, Global tuberculosis control: WHO report 2011, 2011: Geneva, Switzerland). In addition, in 2011 almost one million TB-associated deaths occurred among HIV uninfected (HIV−) individuals and about 0.43 million deaths among HIV-infected (HIV+) individuals.
In addition to prevention, the cornerstones of TB control are reduction of transmission, morbidity, and mortality all of which require early treatment initiation. This in turn necessitates timely TB diagnosis, underlining the need for new rapid diagnostic tests. Rapid identification of active TB is the key unmet need in TB disease management.
Currently, TB diagnostic tests depend on the detection of M. tuberculosis which, thus, require a specimen from the site of disease which is not always easy to obtain. Furthermore, the current tests for TB are limited by lack of sensitivity (microscopy of sputum smears) or require amplification of M. tuberculosis which takes weeks (culture) and/or is expensive (molecular detection). Moreover, these gold standard tests (culture and molecular detection) require laboratory infrastructure which is not accessible in many endemic regions.
Accordingly, there is a need in the art for novel TB biomarkers that are easily detectable, and neither require a specimen from the site of infection, nor laboratory infrastructure to provide rapid TB diagnosis and limit the spread of the disease.